"Alternative facts" are not facts, they're lies.
Regardless of the political stance of the person asserting it, 2+2 is never 5.
If someone claims 2+2=5 they're lying. Said a billion times, it's still a lie.
No. 2+2=4 for all eternity. What anyone else said or did doesn't change that.
The Leave bus message was a lie. To claim otherwise is to lie. End of story.